From left to right: 26-year-old Latrise Graves and 33-year-old Phillip Martin (Philadelphia Police)

Posted: Aug 10 2015 10:12PM EDT

Updated: Aug 11 2015 05:25PM EDT

PHILADELPHIA--(WTXF)-- - Investigators say a man with autism was being restrained inside a home in Overbrook. According to police, a woman and her boyfriend were holding the man captive.

"He's got a mental capacity of a 5-year-old. As they were feeding him at the hospital, he kept saying to himself, ‘Eat faster, eat faster,’ which is indicative of how he is being treated in the house,” said Philadelphia Police Lt. John Walker.

Police say the row home on the 6400 block of Lebanon Avenue was a more like prison for a man who lived there.

Police tell FOX 29, the 28-year-old man, who is severely autistic and unable to talk was being held against his will, handcuffed and duct taped inside his home by his own sister.

"In the basement of that location was adult diapers and strong owner of urine the house. The house was kind of in deplorable condition. There were two juveniles in the house that we had to take to the Department of Human services and turn them over to them,” said Lt. Walker.

On Sunday, surveillance video shows the man running into a corner store across the street for safety. Police say it happened moments after breaking free from being handcuffed to futon. In the video, you can clearly see the handcuffs still dangling from his wrist. The owner of the store says the man started grabbing food and drinks from the shelves, sat on the floor and started eating, saying he was starving.

The owner of the store says about a month ago the same man came into his store nearly naked and bound with duct tape.

Police say after finding the home in deplorable conditions they arrested the man's sister 26-year-old Latrice Graves and her boyfriend 33-year-old Phillip Martin. According to police, Phillip Martin and Latrise Graves are charged with: Unlawful Restraint, False Imprisonment,Criminal Conspiracy and related offenses; their bail is set at a half a million dollars each.

"His own sister has legal care of him she's been caring for him for many years. The boyfriend and his sister lived together they went out last night and that's why they handcuffed him to the futon," Lt. Walker explained.

The man and the two juveniles in the home are in official custody of the state.